Process of making bituminous emulsions



3 Sheets-Sheet- 1 n, 2 i927@ Ea 5 9 L.. KLRSCHBRAUN PROCESS OF MAKINGBITUMINOUS EMULSNS Filed Nov. 2l. .1919

magos A e v 192K Hm 25 L. KlRscl-IBRAUN PROCESS OF MAKING' BITUMINOUSEMULSIONS 3 Sheets-Sheet 2 Filed Nov. 2l, 1919 L. KIRSCHBRAUN Pnocss oFMAKING BITUMINous EMULsloNs Filed Nov. 21, l1919 s sheets-sheet sPatented Jan. v25, 1927.

PATENT OFFICE.

LESTER XIRSCHIBRAUN,l F CHICAGQ, ILLINIS.

P ROCESS 0F MAKING BITUMINOUS EMULSIDNS.

Application tiled November 21, 1919. Serial No. 389,690.

The present invention resides in a process of makin emulsions of thebitumen-pltch type in w ich the temperature of the mass undergoingdispersion is maintained at such a oint that the bitumen-pitch type basewiil be dispersed without a substantial amount of coalescence.

In the drawings:

Figs. v1, 1A and 1B taken together indicate a more or less diagrammaticshowing of an apparatus suitable for carrying out the present invention.

Referring to the drawings, 1 designates an emulsifying tank adapted toreceive asphalt or other binderaand an emulsifying agent` such as clayand water. This tank may be of any suitable construction and is providedwith a rotating shaft 2 driven through gears 3 and 4, leading to anysource of power. arms 5 (zo-operating with stationary arms 6 secired tothe side of the emulsier. The obje t of this emulsifier is to form anemulsication of the binder and emulsifying agent such as clay, etc. Inmaking this emulsified composition, the clay is put into the emulsitierand water gradually added until a paste or dougliy mixture is obtained.-Asphalt or other 'pitchy binder is then slowly stirred into this pasteand water' is gradually added from time to time to obtain a workingconsistency.- The water is preferably warm or liot. This mixture isthoroughly beaten up until `the binder is uniformly dispersed throughthe emulsifying agent, the object being to reduce the binder to a veryfine state of division and thoroughly mix it with the clay. It is to beunderstood that other emulsifying agents than clay, may be used and incertain cases other binder might be used such as hereinafter designated.

This mixture contained in the emulsier can be delivered to a beater 7through pipe 8 controlled by valve 9. The beater 7 is' of a constructionadapted for converting stock into pulp and is provided with a suitablebeating roll or arms 10 and 11. The pulp .vhicli I use may be made fromany suitable fibrous material such as paper waste, tan bark, wood pulp,cotton Waste, grassy fibres, and hemp. After the fibre is beaten to apulp, the pulp is delivered by means of pipes l2 and 13 and pump 14 to amixing tank 15. This tank is provided with a mechanical agitator 16driven from any suitable source of power. The emulsified mixture hereto-The shaft 2 carries a series offore referred to instead of beingdelivered to the beater 7. may be delivered direct to the mixing tankthrough pipe 17 controlled by valve 18. If the emulsified composition isdelivered directly to the beater it is closely and thoroughly beateninto amalgamation with the pulp, and if it is delivered directly to themixing tank it is there mixed with the pulp in such a way as tothoroughly amalgainate with the latter. It will be desirable in manycases to add a filler to the mixture which may be of such relativelcheap ma terials as saw dust, sand, groun cork or any suitablecomminuted material. It may be desirable to add more clay to the mixingtank also. The mixture in the tank 15 is thinned to the desiredconsistency by adding as much water as desired through the pipe 19.. Theconsistency of the mixture in the mixing tank will depend upon thecharacter of the product to be formed yand also upon the character ofthe materials in the mixing tank. In the formation of roofingcompositions, the mixture, I have found in certain cases, should besufficiently diluted with water to permit the fibres to more or less Howin thegwater so that they will have opportunities to interlock andinterlace with each other when the water is separated out. It is also'very important that the materials be suiciently mixed to insure athorough amalgamation of the librev with the emulsified binder and withsuch filler, if a filler be used. The materials in question should be somixed that when in an aqueous medium they will be free of any tendencyto be sticky or adhere to the machine. It may be here noted that whenthe emulsified composition is formed, the particles of the binder shouldbe so thoroughly and finely dispersed throu h the aqueous paste that theparticles of t e binder will tend to be thoroughly separated from eachother and surrounded by the clay and water. The operator may ascertainthat the emulsilication has been suicient by man-- -ual manipulation. Ifpro erly emulsiied it with nozzle 22 which is preferably the widthof thesheet desired. The nozzle 22 delivers the mixture to a box 23 whichoverflows into an endless travelling screen 24. This screen 24 which maybe olI a construction similar to those used in the paper makingindustry, or may be a i'oraminated brass belt which is trained aroundrollers 25 and 26. Intermediate idler rollers may be provided asdesired. The upper lap of the belt travels across rollers 27 forming ineiicct a table or support for the belt. At either side the screen isprovided With confining belts 28; it being understood that these beltsserve to prevent the material from flowing over the sides of thetravelling screen.

Preferably spreader or distributing rolls 29 and 30 are provided and theframe spring gripped as shown at 31. As shown in Fig. l, the apparatus'is broken away to reduce the size of the drawings, the endless screen isof suhcient length to allow the desired amounts of Water to drainthrough the screen. To facilitate the removal of the water from thesheet, I provide a plurality of suction boxes 32 and intermediate,pressure rolls 33, a further suction pipe 34 may be provided to removefurther Water if desired.

In forming the sheet passes over the foraminated belt or screen onto acanvas or other fabric belt 35, which is trained around a series ofrolls 36 and driven from any suitable sourceof power. Presser rolls 37may also be provided. The now formed sheet a is threaded up over thebelt 38 to feed rolls 39 and thence up over rolls 40 and 4l to a seriesof drying rolls 42. The belt 38 serves to take up any surplus moistureand it is thereafter dried by passing it around rolls 43.

The belt 35 may be cleaned by means of rotating brushes 44 and suitableWater jets 45. The belt 38 can also be cleaned by brushes 46 and jetnozzle 47, and the screen by brushes 48 and jet nozzle 49. It will beunderstood, however, that one of the important features of the presentinvention is thatl the mixture which is to be sheeted is of suchcharacter that it can be` readily washed oit of the various belts andwill not stick thereto.

After the now formed sheet leaves the rolls 42 it passes through rolls50 to the coating mechanism 51, which is provided with delivery pipe52.for the coating material, and presser rollers 53 which may be of anysuitable construction. If granular faced roofing is being formed, thecoated sheet can be fed beneath hopper 54 containing suitable granularmaterial so as to cover the face of the roofing. The sheet then coatedand covered with granular material is passed between presser rolls 55and thence over cooling rolls 56 to slitting knives 57 carried by roll58. The sheet which is now severed longitudinally may be cuttransversely to form shingles or shingle strips by passing throughtransverse knives 59 carried by rollers (it). lt is to be understood olcourse (hat these knives and rolls are so geared as to operatesynchronously. The shingles or shingle strips are then carried away bytravelling conveyor' belt 61.

The apparatus here shown is adapted for making shingles or shinglestrips of prepared rooting suoli as asphalt shingles and the like, butit is to be understood that the sheet after having been formed may betreated in any desired manner, such for cxample, as having a designprinted thereon, etc.

It may be desirable in certain instances to put a granular facing overthe sheet and dispense with the coating. This may be done by impressinggranular material on the sheet through the hopper 61 While the sheet isstill in sufficiently plastic condition to permit the granular materialto become partially embedded in and adhere to the sheet. ln other casesit may be desirable to give a color or luster to the roofing and thiscan be accomplished by covering thegranular facing of the rooting afterit is applied with a tlm of silica of soda and a pigment or dye, thepigment or dye giving the desired color.

An essential feature of this process resides in the conversion ofasphalt or other bituminous or hydro-carbon material, which is 9normally of an adhesive nature into a finely divided nonadhesive form.This transfermation is accomplished by'a process of dispersion of theasphalt into water by means of an emulsifying agent. The asphalt used issolid or semi-solid at ordinary temperature and is of a charactersimilar to that which is employed for the purpose of waterproofingfelts, fabrics and the like as in the manufacture of prepared rootings.The asphalt may either be a native asphalt, pure or containing mineralmattei' softened, if desired, by means of fluxing oils, or may be theproduct of distillation or oxidation ,of afcphaltic petroleums in a wellknown manner. It is the nature of such asphalts that when they areplaced in contact at moderate temperatures they coalesce or adhere so asto form a coherent and homogeneous mass and this is an essentialcharacteristic of such asphalts as are used in the manufacture of thestock for particular purposes to be referred to hereinafter. In place ofasphalts such as described, I mair also employ tars and pitches ofvegetable, animal or mineral origin, resins or resinous materialssoftened. il' desired, with tempering oils so as to bring them to theproper consistency for the purpose intended, and such substances are re`garded as comprehended by the terni bitu' men or bitumen-pitch type baseas cmployed in my claims. Heretofore While il has been proposed to formvarious waterproof compounds containing libres to be made or produced inblock or in sheet form.,

suchmaterials could not readily be used in connection with the usual webforming nachines such as are employed for example in the'manufacture offelt 0r paper for the reason that the stock including the containedasphalt was of such an adhesive nature as to cause the gumming of themachinery and blankets. Of course if the pitch be of such solidity atordinary temperatures that il 1s capable of being ground or comminutedlike gilsonite it may be mixed with libre just as particles of charcoalare mixed, but in that event such pitchy particles are not adhesive atordinary temperatures at which the stock is maintained when the web isbeing formed into paper, and the subsequent evaporation of the water orsubjection of the web to pressure would not cause the coalescence of thepitchy particles in the web, and the Waterproofing of the fibres.

While the asphalt herein referred to is designated as being solid orsemi-solid at atmospheric temperatures, nevertheless, it is well knownthat materials of this characterl are scientifically or more correctlyknown to be liquids of exceedingly great viscosity, so that whilecapable ofbeing handled en masse nevertheless they flow slowly atordinary temperatures and require a containing vessel in order toconfine them. Materials of this character are readily liquefiable byheat, exhibiting a gradual decrease in viscosity with the elevation oftemperature. Such solid or semisolid asphalte as require theapplicationof heat as distinguished from liquid asphalts are mostreadily adapted to produce this non-adhesive emulsion. The liquidasphalts, i. e., those capable of being enlulsified without theapplication of heat, while convertible to a relatively non-adhesiveform, are nevertheless easily affected by lthe pressures employed duringthe felting operation and are likely to become sticky under certainconditions When used on the paper machine. The selection of asphalt ofproper character and consistency is an important item in producing thenon-adhesive emulsion. For the purpose of this process as stated before,it is necessary to-convert this adhesive asphalt into a finely dividednonadhesive form in Which it may be mixed with fibre stock and Water andproduce a non-adhesive and non-coherent mixture that is capable of beingflowed into web form in much the same way that ordinary fibre or. paperstock is caused to form a web.

In paper stock it is necessary, as is well known, to have a sufficientquantity of Water in order that the web forming materials may spreadthemselves in a web, and consequently vin any emulsion which is used forthis purpose it is necessary that the water constitutethe external orcontinuous phase so that additional Water may be supplied to form afreely flowing mass, and yet be capable of extraction or expression whenthe web 1s produced. So far as I am aware, with the informationpreviously supplied it has been considered impossible heretofore toproduce an aqueous emulsion of asphalt which is nonadhesive under theconditions prevailing in heating stock and under the pressures employedin forming a web on the paper machine, and it has also been impossibleto prepare an emulsion of this character in which has been carried thelarge amount of asphalt relative to the paper stock which is necessaryto produce completely Waterproofed sheet of felted fibres. I am awarethat emulsion of soaps and resinous materials have been used heretoforefor the purpose of sizing paper stock to make it Water resistant, butsuch emulsions have been used under conditions in which the soluble soapemployed an emulsifying agent is reacted upon chemically prior to theformation of the web so as to break the emulsion and precipitateinsoluble and more or' less non-adhesive soaps Ior resinates upon thefibres. The present process contemplates the use of no chemicals' orreagents which disturb the emulsion or change its non-adhesive charac-4ter at any stage of the operation prior to the complete rem-oval ofWater; the transformation from non-adhesive to adhesive character of theasphalt being accomplished 'only by the removal of Water, through theapplication of pressures or heat, or both.

In order to produce the emulsion above referred to, I use claycontaining a large proportion of colloidal material as an emulsifyingagent but obviously other finely divided powders or colloidal materialswhich produce an emulsion of a non-adhesive character may be used inlieu thereof.

Among the other finely divided powders which may be used Within thecontemplation of the present invention, may be cited fullers earth,mineral pigments, slate dust, ochre, sienna, metallic oxides andhydroxides, and silicates, which produce a viscous plastic mixture withwater.

The emulsion may be produced in batches or by a continuous process. Ifprepared as a batch, I first make a thick aqueous suspension of the clayand heat it to a temperature approximating the melting point of theasphalt Which is to be emulsified. The asphalt is also heated until itis quite fluid, the temperature varying with the viscosity o f theasphalt and its melting point. Preferably a temperature of 300 to 400OF. is employed for the harder varieties of asphalt While for the softervarieties a lower teinperature affords the desired degree of fluidity.The aqueous suspension heretofore referred to is produced in -a vesselhaving means for rapidly agitating the contents thereof. Its consistencyis such that it is too fluid to hold its form but sulliciently viscousto flow slowly through a fair sized orifice. lt is important that theconsistency of this paste be regulated Within more or.

less definite limits as the degree of dispersion obtained during theemulsifying opera tion depends largelyv upon the viscosity or theinternal friction resulting in the agitation of the asphalt throughoutthe viscous clay suspension.

The molten asphalt is gradually added to the viscous suspension Whilethe lnass in the vessel is being subjected to rapid agitation. This isimportant in order to avoid inversion of phase and production of anadhesive emulsion. As the asphalt is introduced and continuouslyemulsified the mass thickens and it becomes necessary to add Water inorder to n'iaintain the desired viscosity of the contents of the vessel.The addition of asphalt is continued, alternating Wit-h the additions ofWater and in such quantities as to maintain this desired consistency. Ifthe vessel is sufficiently large Water and asphalt maybe addedsimultaneously in the desired proportions. lt is advantageous in somecases to introduce the asphalt at a temperature above theiboiling pointof Water as the expansive force of the steam generated upon contact ofthe asphalt With the aqueous suspension produces, by more or lessfoaming, an extension of surface of the pitchy material during itsincorporation. The mechanism of this dispersing operation is somewhat asfollows: As the asphalt strikes the thick aqueous suspension it becomesimmediately subjected to theA agitating arms of the mixer. Thesearms-produce rapid extension and sub-division of the stream of pitchinto very fine threads throughout the mass of clay suspension. Theviscosity of the thick suspension assists in-the formation of thesethreads and their tine degree of attenuation. At the same time theformation of bubbles induced by the steam generated1 assists in theproduction of thin films and threads of the asphaltic material. As thesethreads are being rapidly formed and rapidly attenuated, a point isreached depending upon the temperature -of the mass, its viscosity andrapidity of agitation, at which the threads have become so fine andtheir surface so great that they become rapidly broken and subdividedinto filaments Which in turn become subjected to further subdivisionuntil their length is such that their surface tension causes the minutethreads thus formed to assume a globular or spherical form. Thisdispersion is produced not only under the conditions and by themechanical agency above referred to, but also through the presence .ofthe colloid Which in effect increases the surface tension of the more orless molten pitch'v undergoing disdividual particles with the naked eye.The

average size of the particles is about .0l millimeters. Some of thesmaller particles exhibit distinctive Brownian movement. It should benoted that although the pitch is in liquid condition When introduced,the form of the particles or relation of phases docs not change uponcooling and upon more or less hardening or solidcation of the pitchlaits subsequent reduction to no1'- mal temperatures. The emulsion thusformed has the peculiar characteristic of not being affected to thepoint of rupture by electrolytes but precipitates a positvely chargedcolloid ferrie oxide sol. The emulsion itself is weaklyelectro-negative. It. Will be observed that in the system so producedthe asphalt constitutes the disperse or internal phase While theexternal or continuous phase comprises the Water with the suspended claycolloid. This constitution of phases with the water as the externalphase permits the dilution or admixture of water with thc emulsion inall proportions so that when applied to the fibre -stock the necessaryquantities of water ma be added to accomplish the desired We formingoperation.

lt is important to note that a desirable feature in the preparation ofthis emulsion resides in the degree of dispersion of thc asphaltparticles throughout the continuous phase. The fineness of dispersion isto a considerable extent regulated by the viscosity of the mass, whichif it is desired to keep it fine, should be relatively thick orpastelike, during agitation and by its temperature. For example, if theclay suspension be too thin, and the necessary internal viscosity belacking, the threads formed during the initial stages of dispersion arerelatively coarse and the material thus comminuted may maintain variouscoarse stages of subdivision ranging from relatively coarse threads downto the finer particles. Like- Wise if the temperature of either theasphalt or the suspension is too low, coarse particles are similarlyformed. On the other hand should the temperature of the pitch or thepartially formed material be too great, there is danger of partial orlocal i coalescence 'off the previously formed ma- 1 coating.

'of about 140 melt-ing point, a desirable temterial, due probably to thecomplete removal of water by heatfrom around some of the asphaltparticles at the point of confluence with the incoming hot liquidasphalt. Furthermore care should be taken to have sufficient waterpresent at all times as otherwise the asphalt will agglomerate producingcomplete inversion ot' the phase, the water and clay constituting' theinternal phase with the asphalt as the continuous medium. The degree ofdispersion attained, plays, I believe, an eii'ective part in causing thematerial to retain its non-adhesive character in the highest and mostpersistent degree. The process of dispersion, I believe, results in theformation of heavily absorbed films of Water and clay colloid about theindividual particles of asphalt. I believe that the finer the degree ofdispersion attained and the greater the surface energy thus resulting,the more tenaciously is this protective tilm retained about theparticles, so that in subsequent operations of forming paper, thisprotective coating is not readily broken or disturbed and is onlydisrupted after the water has been tothe largest extent expressed by thedrying of the sheet. The larger the particles, the more easily is thisfilm disturbed in which case such larger particles are more readilyaHected by the pressures employed upon the paper machine and the greaterwill be the tendeney for the asphalt to become adhesive through the easyremoval of the protective I`have found when using asphalt perature atwhich to maintain the clay suspension is about 150 F. and a satisfactorytemperature at which to carry the asphalt is `about 325 to 350 F., thetemperature of the batch being maintained during the addition of the hotasphalt by the introduction of further quantities of water at a properheat to compensate for the temperature oi' the'incoming asphalt.

lVhen it is desired to holdthe temperature of the batch or bulk supplyabove 212 F., in order to more advantageously emulsify very viscousmaterials such -as high melting point oxidized asphalts, the emulsifyingapparatus is sealed and the entire operation is carried on at pressuresabove atmospheric. It is thereby possible to maintain a temperatureabove the boiling point of Water without permitting evaporation orboiling away ot' any substantial quantities of water from the apparatus.

The non-adhesive character of the emulsion and its desirable degree ofdispersion may be roughly ascertained by manual manipulation. A quantityot material when worked between the fingers should feel smooth, plastic,slippery and free from grit'I particles and should exhibit no tendencyfor the particles of as halt to agglomerate among themselves W enpressed or rubbed between the fingers. In fact, the emulsion thusproduced should feel substantially like the thick clay suspensionoriginally employed in its production. It should be readily washed fromthel hands With water and should be capable of dilution in allproportions with further quantities of water. If it should be desired toretain the asphalt particles in suspension to the best possible extent,a protective non-adhesive colloid may be added after the emulsiicationhas been completed.

In order that this emulsion yshould be` capable to the greatest possibleextent of being carried in large lquantities by the fibrous stock, it isdesirable that the proportion of asphalt to clay be large. The amount ofasphalt Which-can thus be emulsified depends considerably upon the clay,apparently varying with the amount of colloidal matter in such clay;thus. clays carrying the largest, amount of colloidal matter beingcapableof carrying the larger amounts of asphalt. By using the properquality of clay I have been able to make an emulsion containing as much'as ten parts of asphalt, by weight, to one part of clay. Ordinarily,however, portions of four or five'parts of asphalt to one part of clawill be found most satisfactory althoug smaller proportions maybe'employed where the amount of asphalt to be contained in the linalpaper product issmall and does not contemplate its complete saturation.An analysis of a typical emulsion made by the operation above indicatedwould show approximately 50%, `by weight, of asphalt,'

10%,b weight of clav and 40%,by wei ht y a y g a ,of water.

I have heretofore described a batch pfocess for producing this emulsionbut I have found Where large quantities are required, that it is mostdesirable to effect its ina-nufacture as a continuous operation. Forthis purpose, I have provided a mixer or an emul sifying apparatusprovided with helica. blades mounted upon a rapidly revolving shaft. Inan initial stage of producing the emulsion this ,apparatus `is chargedwith the aqueous suspension or with finished product as before describedfor batch operation. The

agitation blades are so disposed as to cause a rapid incorporation ofliquids introduced at the top of the vessel with the bulk contents ofthe container.

vAfter the initial charge of suspension or,

mined proportions corresponding to the pro-I Y desired, may be addedsawdust.

instances after the stock has been thorough-A portions desired in thefinal emulsified composition. For example, if an emulsion of thecomposition above described is desired, the aqueous suspension is madeup 1n proportion of one part, by Weight, of clay and four parts, byweight, of Water. Thissuspension is fed to the emulsifier as previouslydescribed continuously and in predetermined quantities andsimultaneously with the introduction of asphalt in like regulatedquantities. By regulation of the volume of the incoming streams ofasphalt and suspended emulsifying agent and by continuous withdrawal ofthe finished product from the system, an emulsified composition of thecharacter above described Will be produced.

In the producing of emulsion thus continuously it is important t0maintain substantially similar conditions of viscosity in thecirculating mass of finshed and surplus emulsion always contained in thesystem. The retention of this quantity of surplus emulsion in the systemacts as a balance wheel against minor variationsof viscosity andtemperature due to momentary introduction of excess of either asphalt orclay suspension. It will be`evident that on account of such minorvariations and the necessity for maintaining nearly constant conditionsof proportions, temperature and viscosity, it is advantageous tomaintain as large a bulk supply of finished emulsion in the system as iscompatible with the rate of introduction of incoming ingredients and theWithdrawal of the finished product from the mixer.

The product of this continuous operation is in all respects the same asthat produced by batch operation previously described. As taken from themixer, it is of viscid consistenc)Y but not so stiff as to prevent itsready egress from the orice provided for its Withdrawal. As fast asproduced this emulsion is preferably thinned with Water so.as tofacilitate its transfer by pumps to the storage tanks and receptacleswherein it is held in suspension for admixture with the paper stock.rl`hese tanks or receptacles in which the emulsion s-stored arepreferably provided with mechanical agitators Which serve the purpose ofmaintaining a uniform suspension of the asphalt throughout the aqueousmedium.

In the manufacture of paper by means of this process the stock isprepared in the usual manner by beating, jordaning and screening.Various stocks may be used such as sulphite, sulphate, rag fibres, mixedpapers, mechanical Wood, leather, to which, if In some l v beaten outthe emulsion may be pumped directly int'o the beaters and circulatedwith 'the stock until a uniform mixture is obtained; or an emulsion maybe added in the stuff chest and likewise subjected to suitable agitationto provide a uniform mixture. I have generally found it preferable,however, to mix the emulsion with the fibre stock at the mixing boxinterposed between the machine chest and the screens. The proportion ofemulsion to stock is readily controlled by valves on the delivery lineor by usual metering devices and its introduction at this pointfacilitates rapid and easy variation of proportions. The mixture thusproduced is preferably kept cold and passes through the screens and tothe How box of the machine whence it is formed into a sheet, exactly asif the stock contained no emulsion. A cold mixture produced bymechanical refrigeration, if desired, affects favorably the nonadhesivequalities otl the emulsion and assists its resistance to pressure duringsheet forming operation. The sheet or web is formed in the usual mannerby felting or interlocking with the fibres on either cylinder or screendepending upon the type of machine, the sheet being successivelysubjected to the action of suction boxes, press rolls and after thedesired amount of water is removed transferred in the usual way to thedryers. During the entire time and at all stages of the passage of thestock over the Wet end of the machine, the asphalt particles retaintheir adsorbed iihns of Water with protecting colloid to such an extentthat the sheet or stock is at all times non-adhesive. Upon reaching thedryers,the residual moisture is gradually removed and the asphaltparticles under the influence of heat and removal of adsorbed films ofWater gradually coalesce forming a more or less continuous phasethroughout the sheet. lvhen operating with a multicylinder machine, itis of course possible to vary the quantity and character of theemulsified ashpalt in any of the plies; for example the outer plies maybe composed of ordinary rosin size stock free from asphalt or may haveintroduced thereinto a colorable pitch while the body plies of the sheetmay contain the usual quantity of black asphalt; likewise, under suc-hconditions it is possible to use a softer asphalt of the same characterin the body plies while embodying a relatively hard and high meltingpoint asphalt for the outer plies. It Will be apparent that Widevariations in character of the resulting product may be effected undersuch conditions producing thereby sheets Which are particularlyadaptable for special uses in Which Waterproof boards or heavy paperscan be applied.

rIhe product of this process is further characterized by the additionalstrength in the resulting sheet over that possessed when the stockitself is formed into a corresponding unsaturated sheet. rl`he strengthis increased almost directly in proportion to the amount of asphaltintroduced. This affords an additional advantage in the roofing artwherein a product of this character containing less than the fullsaturation may subsequently be subjected to the usual process of tanksaturation to take up additional amounts of asphalt and complete itssaturation. A product of this character referred to, on account of itsadditional strength can be run through the machine with great rapidityand has the properties of absorbing additional saturation with greatreadiness.

lIt has heretofore been impossible to undersaturate or partiallysaturate a sheet of dry felt by tank method for the reason thatsaturation proceeds from the outer surfaces of the sheet and if thesheet is not permitted to take on its full saturation, it will be foundthat although the outer surfaces are completely saturated, the innerbody of the paper may remain entirely free from the saturating liquid. Aproduct of the present process when incompletely saturated di'ers inthis respect. The coalesceuce of the individual particles of asphalt andtheir ability to coat the individual fibres constitutes a novel featureof the behavior of the stock thus produced, on the dryers. Even thoughthe amount of asphalt maintained in the Asheet be considerably less thanthat required to produce full saturation, the asphalt colitained thereinis uniformly distributed throughout the body of the sheet as a more orless continuous coating upon the libres. While this is true of the bodyof the sheet, I have found that the surface may under some conditionsbecome more or less freed from the asphalt particles apparently as aresult of their washing off or sucking from the surface as the Web isbeing formed. In such cases although the body of the sheet may containthe asphalt uniformly distributed throughout, the surface or superficialarea may show a mottled appearance due more or less to the removal ofthe asphalt as above described. In certain applications of this process,this affords a valuable feature of the invention, as for instance, inthe case of floor coverings which are to be painted with a decorativecoating. It has hereto-- fore been found difficult in applying suchpaint coatings to ordinary saturated felt, to prevent the asphalt frombecoming dissolved into the paint and discoloring it. The product ofthis invention, with a surface partially deprived of asphalt affords anideal surface uponV which to print with decorative paint.

I have usually carried on in connection with the cylinder or Fourdriniertype of machine in which a drying temperature is used above the boilingpoint of water and sufficient to cause complete coalescence of theindividual particles of asphalt into a continuous film.

I have found it possible, however, to conduct the drying operations insuch a way that the described a drying opera-tion as is A particles ofasphalt, especially when used 1n small proportions, may maintain theirdiscreet form and serve the function of tying together and reinforcingthe fibres and ,acting as a water repelling agent. For 'example, theproduct of this process produced on a wet machine may be dried in adrying room at a relatively lowftemperature and by proper selectionl oftemperature with relation to melting point of asphalt employed, a drysheet may be'obtained in which the asphalt particles maintain theirindividual form, serving the purposes above described.

It will be further noted that the adhesive character of the asphalt. isresumed during the drying operation and isattained only by the removalof Water and by heat and without the use of chemicals or reagents toconvert it to altered form. This result is accomplished b v the purelyphysical means described. 4

I have discovered also that a valuable' feature of the'invention residesin the fact that the addition of the asphalt emulsion as beforedescribed to the paper stock, causes the fibres in their formation to besomewhat bulked; that is to say the particles of asphalt seein to havethe tendency to separate lthe fibres from each other to some extentduring formation without interfering With the felting operation. Vhenthe sheet thus formed reaches the dryers and the asphalt particles beginlto coalesce andspread themselves about the fibres in thin films, -it isapparent that the spacing'produced luy-their origlnal position resultsin a sheet having greater void spaces; and being, in fact, bulked, itfollows that greater yardage of paper results from this bulking fromagiven quantity of stock. I have found in certain instances that thisbulking has produced as much as 60% increase in area or yardage of paperover and above the quantity produced in the usual manner, from anequivlent weight of fibre stock. l

In the preparation of saturated felt as for roofing fabrics, it'has beenthe practice heretofore to employ feltsor felted papers composed largelyof rag fibers. This has been necessary for the reason that such feltsonly appear capable of saturation by im-i mersion in the hot asphalt ina well known manner. The introduction of even small quantities ofother'pa'per stocks such as sulphate news or sulphite substantlallyr'etards saturation and 1t has heretofore been impossible tosatisfactorily saturate felts composed of such stocks. By my process,however, all such limitations are obviated and I may readily use suchsocks as heretofore have not been usable in tank saturated fe'lts. Thesestocks are relatively cheap and their use results in great economy overthe production of saturated felts by heretofore*l known processes.

As an example of proportions used in the practicing of this invention, Itake thirty parts, by Weight, of dry libre stock which may be any of thevarieties of stock heretofore n'icntioned and mix with this, afterbeating out and while contained as a watery pulp, a mixture comprisinglifty-eightparts of asphalt emulsilied with twelve parts, by weight, ofclay contained in its aqueous; vehicle. This proportion of componentswill produce a sheet which is practically completely saturated withasphalt and in character not readily distinguishable from tank saturatedfelt. A sheet of product derived from the above formula and in fact anyproduct of this process, will upon extraction with suitable solvent forasphalt, leave a sheet of dry paper likewise indistinguishable frompaper formed iu the usual manner. lVhile the proportions above statedproduce a substantially saturated sheet, it is desirable in manyinstances and for many purposes to produce a sheet lexis completelysaturated as for example for flooring felt, for wrapping papers,lining,r papers, shoe elements and the like. An example of the formulafor partly saturated stock may be given as follows: To 50% of paperstock of dry weight is added an emulsion composed of 35 parts by weightof asphalt with 15 parts by Weight of colloidal clay contained in itsaqueous vehicle. This will produce a stock suitable for damp proofpapers and by proper selection of the paper stock constitutes acomposition suitable for formation into shoe elements such as countersand the like. It should be noted as a novel feature vof this processthat the amount of asphalt and non-fibrous material which can be carriedby the fibres without interfering with the felting operation may be morethan twice the weight of fibres used. This, I believe, constitutes aradical departure from any heretofore known practices of producing paperwhich permits of the introduction of so large a quantity of' non-fibrousmaterial without interference with the sheet forming or felting`operation.

I have found that the use of this emulsion in stock has a tendencyduring formation of the web to close up the sheet and result in somedifficulty when it is desired to produce a heavy caliper in a singleply. In such instances I have found that the introduction of a smallquantity of sawdust affords the necessary freeness to enable the sheetlto be built into relatively thick calipers with easy removal of thewater.

Iclaim as my invention:

l. The process of producing an emulsion which comprises adding a bitumenin a fluid state to a mixture of clay and water While agitating saidmixture and maintaining its temperature at such a point that the bitumenwill be dispersed without a substantial amount of coalescence of thesame.

2. The process of producing an emulsion which comprises adding a bitumenin a fluid state to a mixture of clay and Water while agitatiug saidmixture and maintaining its temperature at such a point that the bitumenwill not coalesce but Will disperse.

3. rlhe process of producing an emulsion which comprises adding a hotbitumen in a fluid state to a mixture of clay and Water while agitatingsaid mixture and maintaining its temperature at such a point that thebitumen will be dispersed without a substantial amount of eoalescence ofthe same.

4. The process of producing an emulsion which comprises adding asphaltin a fluid state to a mixture of clay and water While agitating saidmixture and maintaining its temperature at such a point that theasphalt. will be dispersed without a substantial amount of coalescenceof the same.

5. rl`he process of producing an emulsion which comprises adding hotasphalt in a fluid state to a mixture of clay and Water while agitatingsaid mixture and maintaining its temperature at such a point that theasphalt will be dispersed without a substantial amount of coalescence ofthe same.

6. A process of producing an emulsion which comprises dispersing abitumen-pitch type base in a fluid state in the presence of a mixture ofdispersive media and water u'hile agitating said mixture, andmaintaining its temperature at such a point that the bitumen-pitch typebase will be dispersed without a substantial amount of coalescence ofthe same.

7. A process of producing an emulsion which comprises dispel-sing abitumen-pitch type base in a fluid state in the presence of a mixture ofmineral dispersive media and water while agitating said mixture, andmaintaining its .temperature at such a point that the bitumen-pitch typebase will be dispersed without a substantial amount of coalescence ofthe same.

8. A process of producing an emulsion which comprises dispersing abitumen-pitch type base in a fluid state.in the presence of a mixture offinely divided powder-like material and water While agitating saidmixture, and maintaining its temperature at such a point that thebitumen-pitch type base will be dispersed without a substantial amountof coalescence of the same.

9. A process of producing an emulsion which comprises dispersing abitumen-pitch type base in a fluid state in an aqueous medium bysubjecting same to agitation in the presence of a mineral dispersivemedia in aqueous suspension, and regulating the fineness of dispersionby controlling the viscosity of the mass during agitation and lill)maintaining the temperature at such a point that the bitumen-pitch typebase will be distype base in a1 fluid state in an aqueous inc- I thatthe bitumen-pitch type base will be dis-v 'low that at which dium bysubjecting same to agitation in the presence of a mineral dispersiveinedia tak-l ing the form ofi-finely divided powdery niaterial inaqueous suspension7 and regulating the fineness of dispersion bycontrolling the viscosity ofthe mass duringagitation, and maintainingthe temperature at such a point that the bitumen-,pitch type base willbedispersed without a substantial amount of coalescence of the same.

11. A process of producing an emulsion which'comprises dispersing abitumen-pitch type base in a fluid state in the presence of a mixture`of dispersive media and water vwhile agitating said mixture, andcontrolling the temperature of the mass during agitation so as tomaintain the bitumen-pitch type base in an extensible condition while it1s being dispersed, producing dispersion of' the base without asubstantial coalescence of the saine. p

12. A process of producing an emulsion which comprises dispersing a`bitumen-pitch type base in a fluid state in the presence of a mixtureof dispersive media and water while agitating said mixture, andmaintaining its temperature at such a point that the bitumenpitch type`basewill be dispersed without asubstantial amount'of coalescence of thesame by the introduction of water into the mass at a temperaturecompensating' for the temperature of the incomin base material.

13. A process of pro ucing an emulsion which comprises dispersing abitumen-pitch type base liquefied byheat in the presence of a mixture ofmineral dispersive media and water while agitating said mixture, audmalntaining its temperature at such Va point persed without asubstantial amountoicoalescence of the same. l

14. A vprocess of producing whicli'comprises dispersing a bitumen-pitch.fi/Pe i mixture ofcdispersive media and water while base in a Huidstate in the presence of a agitating said mixture, and maintaining itstemperature at such a point that the bitumenpitchl typeabaselwill bedispersed without a' substantial :amount of coalescence of.l the' same,said tem erature being materially be- `the bitumen-pitchv base isintroduced.. Y v

15. A process l:of I producing an emulsion which comprises .dispersing abitumen-pitch t base in a fluid state ,in the resence of-a mixture ofdispersive media an water while an@ emulsion?" "bitumen-.pitch type basein heated liquid conmaterial in aqueous suspension, and maintaining itstempera-ture at such a point that the b'itumenitch type base will bedispersed without a su stantialamount of eoalescence of the same, saidtemperature being materially below that at which the bitumen-pitch type.base is introduced.

17. A process of producing an emulsion which comprises adding abitumen-pitch type base in a fluid state to a mixture of an aqueousmedium and a mineral dispersive media taking the form of finely dividedpowdery material in aqueous suspension while agitating said mixture andmaintaining its temperature at Such a point that the bitumen-pitch typebase will be dispersed without a substantial amount of coalescence ofthe same, the proportions of the bitumenpitch type base relative to thedispersive media being in excess of tive to one on the basis of weight.p p

18. A process of producing an emulsion which comprises dispersing abitumen-pitch type baseA in heatv liquetie y`condition in ailaqueousmedium by subjecting same to agif tation in the presence ofmineral dispersive lmedia in aqueous suspension, introducing an aqueoussuspensionof mineral dispersive mediaA ata temperature materially belowthat atv which the bitumen pitch base is introduced,`v Yand controllingthe temperature of the mass undergoing ispersion to produce Adispersion`of said base without a substantial amountof coalescence-of the same.

19.511 process lofvproducing an emulsion,

'whicllicomprises dispersing a'heat liqueiiable dition'by subjectingsame to agitation in the presence of a dispersive media in aqueousmixture', introducing said-aqueous mixture of-dis ersivev media. at atemperature materially elow that at which the` heat liquefied materialis introduced, and controlling the temperature of the mass duringagitation so as to maintain the bitumen-pitch type .base in anextensible condition, producing dispersion 'ofthebase- Without asubstantial coalescence of( the same. Y

LESTE i;IRsoHBRAUN.

